Hackerrank – Problem description
The problem description – Hackerrank.
Solution
The implementation is specific based on a programming language – the features in libraries for date manipulation.
I found out from given date, what is the next sunday. Then I added 7 days to the sunday’s date, to have next sunday. I was cautioned for cases where the sunday is 25th day in a month (e.g. march). Next would be 32nd, which is invalid date. This date needs to be “translated” to next possible date in next month (would be 1st of April in our case). I repeat the process until I reach upper date constraint.
I created solution in:
All solutions are also available on my GitHub profile.
Ruby
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 |
require 'date' def create_next_start_month(year, month, day) if day != 1 day = 1 if month == 12 month = 1 year += 1 else month += 1 end end return Date.new(year, month, day) end def valid_date?(year, month, day) return false if month > 12 max_days = month_days(year, month) return false if day > max_days return true end def month_days(year, month) case month when 1, 3, 5, 7, 8, 10, 12 return 31 when 4, 6, 9, 11 return 30 else if is_leap(year) return 29 else return 28 end end end def is_leap(year) return year % 400 == 0 if year % 100 == 0 return year % 4 == 0 end def create_valid_date(year, month, day) new_day = nil new_month = nil new_year = year if month > 12 new_month = month - 12 new_year += 1 else new_month = month end max_days = month_days(new_year, new_month) new_day = day if(max_days < new_day) new_day = new_day - max_days new_month = new_month + 1 end if(new_month > 12) new_month = new_month - 12 new_year += 1 end return new_year, new_month, new_day end def count_sundays(date_from, date_to) n = 1 sundays = 0 temp_date = Date.new(date_from.year, date_from.mon, date_from.day) while (temp_date <=> date_to) <= 0 sundays += 1 if temp_date.wday == 0 temp_date = date_from >> n n += 1 end return sundays end gets.chomp.to_i.times do (year, month, day) = gets.chomp.split.map{ |e| e.to_i } if valid_date?(year, month, day) date_from = create_next_start_month(year, month, day) else (year, month, day) = create_valid_date(year, month, day) date_from = create_next_start_month(year, month, day) end (year, month, day) = gets.chomp.split.map{ |e| e.to_i } if valid_date?(year, month, day) date_to = Date.new(year, month, day) else (year, month, day) = create_valid_date(year, month, day) date_to = Date.new(year, month, day) end puts count_sundays(date_from, date_to) end |